Subset and superset checks in Python - Mini Project: Build & Apply

Subset and Superset Checks

📖 Scenario: You are organizing a small book club. You have a list of books that the club owns and a list of books a member owns. You want to check if the member's books are all part of the club's collection or if the club's collection is fully included in the member's books.

🎯 Goal: Build a program that checks if one set of books is a subset or superset of another set.

📋 What You'll Learn

Create two sets of books with exact titles

Create a variable to hold the member's book set

Use subset and superset checks with the correct set methods

Print the results clearly

💡 Why This Matters

🌍 Real World

Checking subsets and supersets is useful when comparing collections, like checking if a user's permissions are included in a system's allowed permissions.

💼 Career

Understanding set relationships helps in data filtering, access control, and managing groups in software development and data analysis jobs.

1

Create the book sets

Create a set called club_books with these exact book titles: 'Pride and Prejudice', '1984', 'To Kill a Mockingbird', 'The Great Gatsby'.

Python

# Create the set club_books with the given book titles
# Your code here

Hint

Use curly braces {} to create a set with the exact book titles inside quotes.

2

Create the member's book set

Create a set called member_books with these exact book titles: '1984', 'The Great Gatsby'.

Python

club_books = {'Pride and Prejudice', '1984', 'To Kill a Mockingbird', 'The Great Gatsby'}
# Create the set member_books with the given book titles
# Your code here

Hint

Use curly braces {} to create the set with the exact book titles inside quotes.

3

Check subset and superset

Use the set methods issubset() and issuperset() to create two variables: is_subset to check if member_books is a subset of club_books, and is_superset to check if club_books is a superset of member_books.

Python

club_books = {'Pride and Prejudice', '1984', 'To Kill a Mockingbird', 'The Great Gatsby'}
member_books = {'1984', 'The Great Gatsby'}
# Create is_subset and is_superset using issubset() and issuperset()
# Your code here

Hint

Use variable = set1.issubset(set2) and variable = set1.issuperset(set2) to check the relationships.

4

Print the results

Print the values of is_subset and is_superset with clear messages using print().

Python

club_books = {'Pride and Prejudice', '1984', 'To Kill a Mockingbird', 'The Great Gatsby'}
member_books = {'1984', 'The Great Gatsby'}
is_subset = member_books.issubset(club_books)
is_superset = club_books.issuperset(member_books)
# Print the results with clear messages
# Your code here

Hint

Use print(f"message {variable}") to show the results clearly.

Practice

1. Which of the following statements correctly describes a subset in Python sets?

easy

A. All elements of set A are in set B.

B. Set A has more elements than set B.

C. Set A and set B have no common elements.

D. Set A and set B have exactly the same elements.

Solution

1. Step 1: Understand subset definition

   A set A is a subset of set B if every element in A is also in B.

2. Step 2: Match definition to options

   All elements of set A are in set B. states all elements of A are in B, which matches the subset definition.

3. Final Answer:

   All elements of set A are in set B. -> Option A

4. Quick Check:

   Subset means all elements inside another set [OK]

Hint: Subset means every item of one set is inside another [OK]

Common Mistakes:

• Confusing subset with superset
• Thinking subsets must have fewer elements
• Assuming no common elements means subset

2. Which of the following is the correct syntax to check if set A is a superset of set B in Python?

easy

A. A.issubset(B)

B. A <= B

C. A.issuperset(B)

D. A < B

Solution

1. Step 1: Recall superset method

   To check if A is a superset of B, use A.issuperset(B) or A >= B.

2. Step 2: Identify correct option

   A.issuperset(B) uses A.issuperset(B), which is the correct method.

3. Final Answer:

   A.issuperset(B) -> Option C

4. Quick Check:

   Superset check uses issuperset() method [OK]

Hint: Use issuperset() to check if A contains all of B [OK]

Common Mistakes:

• Using issubset() instead of issuperset()
• Using <= or < for superset checks
• Confusing method names

3. What will be the output of the following code?

set_a = {1, 2, 3}
set_b = {1, 2, 3, 4, 5}
print(set_a <= set_b)
print(set_b >= set_a)

medium

A. False\nFalse

B. False\nTrue

C. True\nFalse

D. True\nTrue

Solution

1. Step 1: Evaluate set_a <= set_b

   set_a has elements {1,2,3}, all of which are in set_b, so set_a is subset of set_b, result is True.

2. Step 2: Evaluate set_b >= set_a

   set_b contains all elements of set_a, so set_b is superset of set_a, result is True.

3. Final Answer:

   True True -> Option D

4. Quick Check:

   Subset and superset checks both True [OK]

Hint: <= and >= check subset and superset respectively [OK]

Common Mistakes:

• Mixing up <= and >= operators
• Assuming strict subset/superset without equality
• Forgetting sets can be equal

4. The following code is intended to check if set A is a subset of set B, but it raises an error. What is the problem?

set_a = {1, 2}
set_b = {1, 2, 3}
result = set_a.subset(set_b)
print(result)

medium

A. Sets cannot be compared using methods.

B. The method name should be issubset(), not subset().

C. The sets must be converted to lists first.

D. The print statement is missing parentheses.

Solution

1. Step 1: Identify method name error

   The correct method to check subset is issubset(), not subset().

2. Step 2: Confirm correct usage

   Using set_a.issubset(set_b) returns True or False without error.

3. Final Answer:

   The method name should be issubset(), not subset(). -> Option B

4. Quick Check:

   issubset() is correct method name [OK]

Hint: Use issubset(), not subset(), to check subsets [OK]

Common Mistakes:

• Using wrong method names
• Thinking sets need conversion to lists
• Confusing print syntax errors

5. Given two sets:

set_x = {2, 4, 6, 8}
set_y = {4, 6}

Which of the following expressions will return True for checking if set_y is a proper subset of set_x (subset but not equal)?

hard

A. set_y < set_x

B. set_y >= set_x

C. set_x.issubset(set_y)

D. set_y.issuperset(set_x)

Solution

1. Step 1: Understand proper subset

   A proper subset means all elements of set_y are in set_x, and sets are not equal.

2. Step 2: Analyze options

   set_y < set_x uses < operator which checks proper subset (subset but not equal). set_y >= set_x checks superset (wrong direction). set_x.issubset(set_y) reverses the sets (wrong). set_y.issuperset(set_x) is wrong (issuperset).

3. Final Answer:

   set_y < set_x -> Option A

4. Quick Check:

   Proper subset uses < operator [OK]

Hint: Use < for proper subset (subset but not equal) [OK]

Common Mistakes:

• Using >= which checks superset
• Reversing the subset direction
• Confusing issubset() with issuperset()